1. Field of the Invention
The present invention relates to a padlock with a releasable lock cylinder inside the body of the padlock. The lock cylinder is releasable from the lock body by using a control key.
2. Brief Description of the Related Art
A very common padlock comprises a lock cylinder inside its body. The structure is such kind that the cylinder cannot be removed from the body. Another padlock type has a structure that allows the removing of the lock cylinder when the padlock has been opened with a key. Yet another type of padlocks have been designed to be useable with a normal key for a normal use and with a control key for removing the lock cylinder. U.S. Pat. No. 4,776,187 describes this kind of padlock.
The lock body of the embodiment of U.S. Pat. No. 4,776,187 is divided into two parts. The shackle of the padlock is connected to the first part. The second part comprises a cavity for a lock cylinder, a cam member, and one locking ball. When using the padlock normally, a normal key is used for opening the padlock by turning the key clockwise. A control key is used for releasing the cylinder from the lock body by turning the control key counter clockwise. The turning of the control key makes it possible to separate the parts of the lock body. The separation in turn allows the removal of the cam member, the locking ball and the lock cylinder away from the second part. In this way the cylinder can be changed to a new one, and the old cylinder can be maintained. The control key is needed for releasing the lock cylinder, because it is desired that the user having the normal key do not have an access to change the lock cylinder. In this way only a limited number of maintenance persons can change and maintain the lock cylinder.
So, when the cylinder lock is taken away from the lock body, the cam member and the other of the locking balls are taken away as well. These parts are easy to lose when taking out of the lock. The padlocks are used at a number of different places. The places are often distance locations, so the cylinders are taken away there where the padlocks are. Lighting conditions of the locations, such as warehouses and storage containers, are often poor. So, it is very easy to drop small parts like the cam members and the locking balls onto the ground where they get lost into the underbrush, sand, roll into a sewer hole of a warehouse area, and so on. Therefore a maintenance man should have spare parts with him, which creates additional costs. So when changing the lock cylinder of the padlock the maintenance man must be careful.